1. Field of the Invention
The present invention relates to a washing/drying method and a washing/drying apparatus suitable for a thorough washing and/or drying of a material to be washed, such as precision electronic parts and precision electronic device parts, which must be thoroughly washed in the preparation steps thereof (i.e., thorough washing) and, from the standpoint of production efficiency or corrosion resistance, in which the washing liquid after washing must be removed by drying within a short time.
2. Description of the Related Art
In the prior art, the thorough washing in the preparation steps of precision parts and electronic device parts, where an attachment of contamination or dust can not be allowed, has been practiced primarily by washing with a fluorocarbon.
As the detergent for such a thorough washing, other than a fluorocarbon, there is known a solvent of the chlorine type such as trichloroethylene, but in the case of a metal product, the chlorine liberated in the washing step may be adhered and cause rusting, and in the case of a resin or rubber product, a deformation or dimensional change due to swelling may occur, and thus a problem arises of an adverse affect on the product. In contrast, in the case of a fluorocarbon, no such problem arises and drying occurs within a very short time, and therefore, washing with Freon 113 (fluorocarbon manufactured Mitsui Dupont Fluorochemical Co. Ltd.) has been employed in the prior art.
A fluorocarbon is harmless to human beings and animals but destroys the ozone layer, which has become a worldwide problem in recent years, and in the interests of environmental protection on a global scale the tendency is now toward completely abolishing the use of fluorocarbon. From such a standpoint, as an alternative to the washing method using a fluorocarbons, the development of a washing water which will not need regulation in the future is now under way.
The critical point of thorough washing, in addition to a thorough cleaning ability, is that the drying after washing can be carried out rapidly and thoroughly. Also, there should be no adverse affect on the material to be washed, as in the case of a detergent of the chlorine type mentioned above.
When washed with water, it is necessary to prevent the precision electronic part, constituted of a metal, from rusting. Since the boiling point of water is as high as 100.degree. C., compared with that of Fron 113, which is 47.degree. C., it is difficult to vaporize, and a part with a complicated shape or a blind tap hole can not be dried within a short time and without difficulty.